The standard HYIP has a site with marketing plans and a personal account. Usually HYIP promise nearby 1-2 % profits daily or even more. In a reality only individual HYIPs more or less stably pay some time
Actually, all HYIP can be divided into 3 groups:
Ponzi - the financial pyramids paying early investors using the investments of later investors. As soon as receipts from investors run low, the site disappear or simply cease to pay money.
Scam - other form of swindle. Don't pay at all.
Paying HYIPs - less than 5%. These projects exist not for long too. Interest rate is more real, for example, 0,1-0,2% daily. Such projects are difficult for find and difficult to count on long cooperation.